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Battle of Walaja
The setting
Walaja, southern Mesopotamia (Iraq), near the Euphrates
Open desert-edge plain that favored cavalry, with folds of ground deep enough to conceal Khalid's flanking horse until they were committed
Reveal the outcome
Recorded sideRashidun Caliphate
Recorded resultvictory
Decisive Rashidun victory; the Sassanid force in the field was destroyed and lower Iraq opened to the Arabs
How the atlas explains it
Khalid pinned the Sassanid army with his center while two cavalry wings, hidden behind folds of ground, swung wide and closed on the Persian rear - a double envelopment that trapped the enemy between the fixing force in front and the encircling horse behind. It is the same shape as Cannae, executed with fast Arab cavalry, and it wrecked the Sassanid force as a fighting body.
What followed
One of Khalid's opening victories in the conquest of Sassanid Iraq, clearing the way into the Sawad, the rich farmland of lower Mesopotamia, and setting up the run of wins that would carry the Arabs to the Persian heartland.